prompt="请输入观众年龄,\n(输入'quit'停止判断):"
active = True
while active:
    age =input(prompt)
    if age == 'quit':
        active = False
        continue
    age = int(age)
    if age <3:
        print(f"{age}岁的观众收费0美元")
    elif age<12:
        print(f"{age}岁的观众收费10美元")
    else:
        print(f"{age}岁的观众收费15美元")